Detection and quantitation of Fetomaternal Transfusion (FMT)
Fetal cell detection in maternal blood represents an important area of laboratory support to the obstetrical management of women. Commonly, quantification of fetal red blood cells (RBCs) is used to estimate the extent of Feto-maternal Transfusion during pregnancy caused by threatened miscarriage, or trauma with placental injury. It is also a valuable tool in monitoring cases of RhD incompatibility between the fetus and the mother for prevention of Hemolytic Disease of the Newborn (HDN). A fast, specific and accurate routine test is needed to quantify fetal RBC contamination in peripheral maternal blood.

Old established method - Kleihauer-Betke test Many clinical laboratories still continue to perform FMT estimations using variations of the slide-based microscopic counting method of acid elution known as the Kleihauer-Betke test. Although this assay is clinically useful, it is laborious and suffers from subjectivity and inaccuracy. The test has a tendency to overestimate the extent of FMT due to an unpredictable number of maternal Hemoglobin F (HbF) containing RBCs that are counted within the population of fetal cells. New alternative method - The Fetal Cell Count™ kit In recent years, several reports have demonstrated the use of flow cytometry as an accurate, sensitive and reliable substitute for the Kleihauer-Betke test. The Fetal Cell Count™ kit, developed by IQ Products, is a unique concept for the detection of fetal cells in maternal circulation based on flow cytometry. It offers direct detection of two intracellular antigens. One antibody is directed against fetal hemoglobin (HbF), which is present in fetal RBCs and in a small amount in adult maternal RBCs (called F-cells). The second antibody is directed against Carbonic Anhydrase (CA), an enzyme that only presents in adult RBCs, and very late stage fetal cells (38-40 weeks of gestation). Thus a clear separate population of fetal RBCs can be identified and quantitated. IQ Products has a patent pending on this application. Right: An example of the distinct populations obtained using the IQP - FCC kit.